Regarding the second part of the argument, some worry that a policy designed to prick an emerging bubble could have unintended negative consequences. Opponents of bubble-popping often cite the example of the Great Depression, claiming it was exacerbated by the Fed’s overzealous attempts to rein in speculative stock market excesses. A counterargument is provided by Borio and Lowe (2002), who perform an exhaustive historical study of financial market bubbles in many countries. According to the authors, opponents of bubble-popping fail to take sufficient account of the asymmetric nature of the costs of policy errors when faced with a suspected bubble: “If the economy is indeed robust and the boom is sustainable, actions by the authorities to restrain the boom are unlikely to derail it altogether. By contrast, failure to act could have much more damaging consequences, as the imbalances unravel” (p. 26). They also argue that emerging bubbles can be more readily identified if central banks look beyond asset prices to include other variables that signal a threat to financial stability. Specifically, they find that episodes of sustained rapid credit expansion, booming stock or house prices, and high levels of investment, are almost always followed by periods of stress in the financial system.